Previous kidney injury poses pre-eclampsia risk factor

Action Points

History of acute kidney injury may lead to adverse pregnancy outcomes, even if the woman has normal renal function before pregnancy.

Note that after adjusting for various patient factors, past episodes of acute kidney injury were linked to a 5.9-times increased risk for pre-eclampsia and a 2.4-times increased risk for adverse fetal outcomes.

History of acute kidney damage may lead to adverse pregnancy outcomes, even if the woman has normal renal function before pregnancy, researchers reported.

In a database review, women with a history of recovered acute kidney injury (AKI) had an increased rate of pre-eclampsia (23% versus 4%, P<0.001) and delivered infants earlier (37.6 weeks versus 39.2 weeks, P<0.001) than women with a history of normal kidney function, according to Jessica Sheehan Tangren, MD, of Massachusetts General Hospital (MGH) in Boston, and colleagues.

After adjusting for various patient factors, past episodes of AKI were linked to a 5.9-times increased risk for pre-eclampsia (95% CI 3.5-9.7), and a 2.4-times increased risk for adverse fetal outcomes (95% CI 1.6-3.7), they wrote in the Journal of the American Society of Nephrology.

"We believe that this study highlights an important finding that will be useful for medical providers caring for reproductive-age women," Tangren stated.

In addition, "Our study demonstrates that a previous episode of acute kidney injury, despite clinical recovery of renal function, is a risk factor for adverse maternal and fetal outcomes in pregnancy. This remained significant despite multiple methods to adjust for confounding including a multivariate logistic regression, a matched analysis, and multiple subgroup analyses," the authors wrote.

They hypothesized that the results may help explain the disparate rates of pre-eclampsia across the globe, which currently range from 1%-15% in various regions.

For this retrospective study, women with (n=105) and without (n=24,640) a history of AKI were included to assess whether a previous episode of acute kidney damage led to subsequent unfavorable maternal and fetal outcomes. All women delivered infants from 1998 to 2007 at MGH, and were similar in respect to factors such as age, BMI, marital status, and education.

Women in the control group were more likely to self-report being a nonwhite race (34% versus 45%, P=0.04). Those with a history of acute kidney damage had a higher rate of preexisting diabetes (12% versus 3%, P<0.001). Pre-conception creatinine concentrations were similar between women with and without a history of AKI (0.70 mg/dl versus 0.69 mg/dl, P=0.36). AKI was defined as a rise in serum creatinine concentration to 1.5-fold above baseline.

A majority of the patients had hemodynamic injury characterized primarily as acute tubular necrosis or pre-renal azotemia (40%) or drug-induced renal injury (12%), the authors explained.

AKI developed as a complication of a prior pregnancy in 12% of women in the cohort. "This encompassed both AKI from severe hyperemesis gravidarum, pre-eclampsia/HELLP syndrome, and obstetric hemorrhage,"they stated.

Also, post-renal etiologies accounted for 5% of AKI in the cohort. In 31% of patients who met criteria for recovered AKI, an etiology could not be determined based on review of the medical record, however elevation of serum creatinine meeting the criteria for AKI was documented, they noted.

In addition to earlier delivery, women with recovered AKI had increased rates of small-for-gestational-age births compared with the control group (15% versus 8%, P=0.013).

According to the researchers, "their findings raise the concern that because these women have normal eGFR estimates prior to conception, they may not be identified as high-risk for adverse pregnancy outcomes."

"Our goal in future studies is to address why women with a history of acute kidney injury are at higher risk for pregnancy complications and to identify strategies to lower their risk," Tangren stated.

Tangren and two co-authors disclosed support from the NIH.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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